What is the chemical composition of food. What else do foods that are useful for the human body consist of? Milk and dairy products

CLASSIFICATION OF FOOD PRODUCTS

Depending on the raw materials and peculiarities of use, food products are divided into the following groups: vegetables and fruits; sugar, starch, honey, confectionery; grain processing products; flavor products; fish products; meat products; dairy; dietary fats.

In public catering, food products are classified according to storage conditions: meat and fish; milk fat; gastronomic; dry; vegetables and fruits.

Food products are divided into types and varieties. Product type due to its origin or receipt, and grade- quality level in accordance with the requirements of the standard. Types and varieties of products make up the assortment.

Topic: Nutritional value of food.

CHEMICAL COMPOSITION OF FOOD

To maintain a normal life, a person needs food. Food contains substances that serve to build the cells of the human body, provide it with energy and contribute to the flow of all life processes in the body.

Chemical composition of most food products complex and varied.

The composition of food products includes: water, minerals, carbohydrates, fats, proteins, vitamins, enzymes, organic acids, tannins, glycosides, aromatic, coloring compounds, phytoncides, alkaloids.

All these substances are called food. The chemical composition, nutritional value, color, taste, smell and properties of food products depend on their content and quantitative ratio.

According to the chemical composition, all food substances are divided into inorganic- water, minerals and organic - carbohydrates, fats, proteins, vitamins, enzymes, etc.

Water(H 2 0) is an integral part of all food products. She plays important role in the life of the human body, being the most significant component of all its cells (2/3 of the human body weight). Water is the medium in which the cells of the body exist and the connection between them is maintained, it is the basis of all fluids in the human body (blood, lymph, digestive juices). With the participation of water, metabolism, thermoregulation and other biological processes. Together with sweat, exhaled air and urine, water removes from the human body harmful products exchange.

Depending on age, physical activity and climatic conditions daily human need for water is 2 ... 2.5 liters. With drinking, 1 liter of water enters the body, with food - 1.2 liters, about 0.3 liters is formed in the body in the process of metabolism.

In products, water can be in free and bound states. It is found in free form in cell sap, intercellular space, on the surface of the product. Bound water is in combination with the substances of the products. When they are cooked, water from one state can pass into another. So, when cooking potatoes, free water turns into bound water in the process of starch gelatinization.

The more water in the product, the lower its nutritional value and the shorter the shelf life, since water is a good environment for the development of microorganisms and enzymatic processes that result in food spoilage. All perishable products (milk, meat, fish, vegetables, fruits) contain a lot of moisture, while non-perishable ones (cereals, flour, sugar) contain little.

The water content of each food product - humidity - must be defined. Reducing or increasing the water content affects the quality of the product. So, the presentation, taste and color of carrots, herbs, fruits and bread deteriorate with a decrease in humidity, and cereals, sugar and pasta - with its increase. Many products are able to absorb water vapor, i.e., they are hygroscopic (sugar, salt, dried fruits, crackers). Since moisture affects the nutritional value, presentation, taste, color of food products, as well as the terms and conditions of storage, it is an important indicator in assessing their quality.

The moisture content of the product is determined by drying its specific sample to constant weight.

Water used for drinking and cooking must meet certain standard requirements. It should have a temperature of 8 ... 12 ° C, be transparent, colorless, without foreign odors and tastes. The total amount of mineral salts should not exceed the norms established by the standard.

The presence of magnesium and calcium salts makes the water hard. Hardness depends on the content of calcium and magnesium ions in 1 liter of water. According to the standard, it should not exceed 7 mg / l (7 mg in 1 liter of water). Vegetables and meat are poorly boiled in hard water, since the protein substances in the products form insoluble compounds with alkaline salts of calcium and magnesium. In hard water, the taste and color of tea deteriorates. When boiled, hard water forms scale on the walls of cooking pots and kitchen utensils, which necessitates frequent cleaning.

According to sanitary standards, no more than three Escherichia coli are allowed in 1 liter of drinking water, and no more than 100 microbes in 1 ml. Drinking water should be free of pathogenic bacteria.

MINERALS

Mineral (inorganic) substances are an obligatory component of food products, in which they are present in the composition of mineral salts, organic acids and other organic compounds.

In the human body, minerals are among the irreplaceable, although they are not a source of energy. The significance of these substances lies in the fact that they are involved in the construction of tissues, in maintaining the acid-base balance in the body, in the normalization of water-salt metabolism, in the activity of the central nervous system, and are part of the blood.

Depending on the content in food products, minerals are divided into macroelements, which are found in relatively large quantities in foods, microelements, contained in small doses, and ultramicroelements, the amount of which is negligible.

Macronutrients. These include calcium, phosphorus, magnesium, iron, potassium, sodium, chlorine, sulfur.

Calcium(Ca) is necessary for the body to build bones, teeth, the normal functioning of the nervous system and the heart. It affects human growth and increases the body's resistance to infectious diseases. Calcium salts are rich in dairy products, eggs, bread, vegetables, legumes. The daily requirement of the body for calcium is on average 1 g.

The average daily physiological need of a person for basic nutrients ah hereinafter is given in accordance with SanPiN 2.3.2.1078 - 01 for a conditional (average) person with an energy value of the diet of 2,500 kcal per day.

Phosphorus(P) is part of the bones, affects the functions of the central nervous system, is involved in the metabolism of proteins and fats. The largest amount of phosphorus is found in dairy products, especially cheeses; in addition, phosphorus is found in eggs, meat, fish, caviar, bread, legumes. The body's daily need for phosphorus is on average 1 g.

Magnesium(Md) affects neuromuscular excitability, cardiac activity, has a vasodilating property. Magnesium is an integral part of chlorophyll and is found in all foods. plant origin. Of animal products, it is most found in milk and meat. The daily requirement of the body for magnesium is 0.4 g.

Iron(Fe) plays an important role in the normalization of blood composition. It is necessary for the life of animal organisms, is part of hemoglobin and is an active participant in oxidative processes in the body. The source of iron are products of plant and animal origin: liver, kidneys, eggs, oatmeal, rye bread, apples, berries. The daily requirement of the body for iron is 0.014 g.

Potassium (K) regulates water exchange in the human body, increasing the excretion of fluid, improves heart function. There is a lot of potassium in dry fruits (dried apricots, apricots, raisins, prunes), peas, beans, potatoes, meat, milk, fish. The body's daily requirement for potassium is 3.5 g.

Sodium(Na), like potassium, regulates water metabolism, retaining moisture in the body, maintains osmotic pressure in tissues. The sodium content in foods is negligible, so it is administered with table salt (NaCl). The body's daily need for sodium is 2.4 g (10 ... 15 g of table salt).

Chlorine(Cl) is involved in the regulation of osmotic pressure in tissues and in the formation of hydrochloric acid(HC1) in the stomach. Basically, chlorine enters the body due to salt added to food. The body's daily need for chlorine is 5-7 g.

Sulfur(S) is part of some amino acids, vitamin B 1g of the hormone insulin. Sources of sulfur are peas, oatmeal, cheese, eggs, meat, fish. The body's daily requirement for sulfur is 1 g.

Microelements and ultramicroelements. These include copper, cobalt, iodine, fluorine, zinc, selenium, etc.

Copper(Si) and cobalt(Co) are involved in hematopoiesis. They are found in small quantities in animal and vegetable foods: beef liver, fish, beets, etc. The body's daily requirement for copper is 1.25 mg, for cobalt - 0.1 ... 0.2 mg.

Iodine(I) participates in the construction and operation thyroid gland. With insufficient intake of iodine, the functions of the thyroid gland are disturbed and goiter develops. The largest number iodine is found in sea ​​water, seaweed and fish. The daily requirement of the body for iodine is 0.15 mg.

Fluorine(F) takes part in the formation of teeth and bone skeleton. Most fluoride is found in drinking water. The body's daily need for fluorine is 0.7 ... 1.5 mg, for zinc - 15 mg, for selenium - 0.07 mg.

Some trace elements that enter the body in doses exceeding the norm can cause poisoning. The standards do not allow the content of lead, zinc, arsenic in products, and the amount of tin and copper is strictly limited. So, in 1 kg of the product, the copper content is allowed no more than 5 mg (except for tomato paste), and tin - no more than 200 mg.

The total daily requirement of an adult human body for minerals ah is 20 ... 25 g.

A favorable ratio of minerals in food is also important. So, the ratio of calcium, phosphorus and magnesium in food should be 1:1:0.5. The most consistent with this ratio of these minerals is milk, beets, cabbage, onions, this ratio is less favorable in cereals, meat, fish, pasta.

Alkaline minerals include Ca, Mg, K and Na. These elements are rich in milk, vegetables, fruits, potatoes. Acid-acting minerals include P, S and O, which are found in significant quantities in meat, fish, eggs, bread, and cereals. This must be taken into account when preparing dishes and choosing side dishes for meat and fish in order to maintain the acid-base balance in the human body. The presence of vitamins contributes to better absorption of minerals.

The amount of mineral substances in the product is judged by the amount of ash remaining after the complete combustion of the product.

When products are burned, organic substances are burned, and mineral substances remain in the form ash (ash substances). The composition of ash and its amount in different products are not the same. The ash content in each product is definite and ranges from 0.05 to 2%: in sugar - 0.03 ... 0.05, milk - 0.6 ... 0.9, eggs - 1.1, wheat flour - 0.5 ... 1.5. In products of plant origin (cereals, vegetables, fruits) there are more ash substances than in products of animal origin (meat, fish, milk). The amount of ash can be increased if the product is contaminated with sand and earth. Ash content is an indicator of the quality of some food products, such as flour. The maximum standards for the content of ash substances in products are given in the standards.

CARBOHYDRATES

Carbohydrates are organic compounds that are composed of carbon, hydrogen and oxygen. The name of these substances is due to the fact that many of them are composed of carbon and water. Carbohydrates are synthesized by green plants from carbon dioxide and water under the influence of solar energy. Therefore, they make up a significant part of plant tissues (80 ... 90% of dry matter) and are found in small quantities in animal tissues (up to 2%).

Carbohydrates predominate in human food. They are the main source vital energy, covering 58 % the body's entire energy requirement. Carbohydrates are part of human cells and tissues, are contained in the blood, participate in defensive reactions body (immunity), affect fat metabolism.

Depending on the structure, carbohydrates are divided into monosaccharides (simple sugars), disaccharides, consisting of two molecules of monosaccharides, and polysaccharides - high-molecular substances, consisting of many monosaccharides.

Monosaccharides. They are simple sugars made up of one carbohydrate molecule. These include glucose, fructose, galactose, mannose. Their composition is expressed by the formula C 6 H 12 0 6 . Monosaccharides in their pure form are crystalline substance white color, sweet in taste, well soluble in water.

Glucose(grape sugar) is the most common monosaccharide. It is contained in berries, fruits, in a small amount (0.1%) in the blood of humans and animals. Glucose has a sweet taste, is well absorbed by the human body, without undergoing any changes in the process of digestion, is used by the body as an energy source, to nourish the muscles, brain and maintain the required level of sugar in the blood. In industry, glucose is obtained from potato and corn starch by hydrolysis.

Fructose(fruit sugar) is found in fruits, berries, vegetables, honey. It is very hygroscopic. Its sweetness is 2.2 times higher than the sweetness of glucose. It is well absorbed in the human body without increasing blood sugar.

Galactose- component milk sugar. It has a slight sweetness, imparting a sweetish taste to milk, is favorable for the human body, does not occur in nature in a free form, and is obtained in industry by hydrolysis of milk sugar.

Mannose found in fruits.

Disaccharides. Disaccharides are carbohydrates made up of two monosaccharide molecules: sucrose, maltose, and lactose. Their composition is expressed by the formula C 12 H220 n .

sucrose(beet sugar) consists of a molecule of glucose and fructose, is part of many fruits and vegetables. Especially a lot of it in sugar beet and sugar cane, which are the raw material for sugar production. Refined sugar contains 99.9% sucrose. It is a colorless crystals of sweet taste, very soluble in water.

Maltose(malt sugar) consists of two molecules of glucose, found in small amounts in natural foods. Its content is increased artificially by sprouting grain, in which maltose is formed from starch by its hydrolysis under the action of grain enzymes.

Lactose(milk sugar) consists of a glucose molecule and a galactose molecule, is found in milk (4.7%), giving it a sweetish taste. Compared to other disaccharides, it is less sweet.

When heated with weak acids, under the action of enzymes or microorganisms, disaccharides are hydrolyzed, i.e. broken down into simple sugars. So, sucrose is split into equal amounts of glucose and fructose:

C12H22O11+H20->C6H1206+C6H12O6

This process is called inversion, and the resulting mixture of monosaccharides is called invert sugar. Invert sugar has high digestibility, sweet taste and high hygroscopicity. It is found in honey, and in the confectionery industry it is used in the production of caramel, halva and fudge to prevent their sugaring during cooking.

The hydrolysis of sucrose under the action of acids of fruits and berries occurs when cooking jelly, baking fruits, and the hydrolysis of maltose occurs during digestion under the action of enzymes of digestive juices.

Mono- and disaccharides are called sugars. All sugars are soluble in water. This should be taken into account when storing and culinary processing of products. The solubility of sugars affects their ability to crystallize (candied). More often sugar, glucose crystallizes (candied honey, jam), fructose does not crystallize due to its high solubility. When sugars are heated to high temperatures, a dark-colored and bitter-tasting substance (caramel, caramel, caramel) is formed. This change in sugars is called caramelization. The process of caramelization explains the appearance of a golden crust during frying, baking and roasting products. Darkening of canned milk or bread crust during baking is due to the formation of dark-colored melanoids as a result of the reaction of sugars and amino acids of proteins.

Microorganisms ferment sugars. Under the action of lactic acid bacteria, lactose is fermented to lactic acid, which occurs during the production fermented milk products(yogurt, cottage cheese). Under the action of yeast, alcoholic fermentation of sugars proceeds with the formation of ethyl alcohol and carbon dioxide, which is observed during the fermentation of dough.

Polysaccharides. These are high molecular weight carbohydrates general formula(C 6 H 10 O 5) ". These include starch, fiber, glycogen, inulin. Polysaccharides do not have a sweet taste and are called non-sugar-like carbohydrates. These substances, in addition to fiber, are a reserve source of energy for the body.

Starch- is a chain consisting of many glucose molecules. This is the most important carbohydrate for a person, in the diet of which it makes up 80% of the total amount of carbohydrates consumed, is a source of energy and causes a feeling of satiety in a person.

Starch is found in many plant products: wheat grain - 54.5%, rice - 72.9%, peas - 44.7%, potatoes - 15%. In them, it is deposited as a reserve substance in the form of peculiar grains with a layered structure, different in shape and size.

Distinguish starch potato, wheat, rice and corn. Potato starch has the largest grains, rice starch has the smallest.

Starch does not dissolve in water. In hot water, starch grains swell, binding a large amount of water and forming a colloidal solution in the form of a viscous thick mass - a paste. This process is called starch gelatinization and it occurs when cooking cereals, pasta, sauces, jelly. During gelatinization, starch is able to absorb 200 ... 400% of water, which leads to an increase in the mass of the product, i.e., the yield of finished dishes. In cooking, this increase in mass is often called a weld (weld of cereals, pasta).

Under the action of acids and enzymes, starch hydrolyzed(break down) to glucose. This process occurs during the digestion of starch in the human body, while glucose is formed and absorbed gradually, which provides the body with energy for a long period. Starch is the body's main source of glucose.

The process of hydrolysis of starch under the action of acids is called saccharification, it is used in Food Industry in the production of molasses. The process of partial saccharification of starch (to obtain intermediate products - dextrins) occurs during the fermentation of the dough, the formation of a dense crust when baking dough products and when frying potatoes.

Starch turns blue with iodine, which makes it possible to determine its presence in products.

Cellulose- a polysaccharide called cellulose and which is part of the cell membranes of plant tissues. Fiber does not dissolve in water, the human body is almost not absorbed. It belongs to the group of dietary fibers (ballast substances), necessary for the regulation motor function intestines, removing cholesterol from the body, creating conditions for the development of beneficial bacteria necessary for digestion. A lot of fiber (up to 2%) is found in vegetables, fruits, cereals, flour products of lower grades. Recently, in laboratory conditions, cellulose has been hydrolyzed with acids to obtain simple sugars that will find industrial applications in the future.

Glycogen- animal starch, found mainly in the liver and muscles. In the human body, glycogen is involved in the formation of energy, breaking down to glucose. Food glycogen is not an energy source, since it is contained in them very little (0.5 %). Glycogen is soluble in water, stained with iodine in a brown-red color, does not form a paste.

Inulin during hydrolysis, it turns into fructose, dissolves in hot water, forming a colloidal solution. Contained in Jerusalem artichoke and chicory root, which are recommended in the diet of patients with diabetes.

The energy value of 1 g of carbohydrates is 4 kcal (the energy value of the main nutrients and food products is given hereinafter according to the data of the reference book "The chemical composition of Russian food products").

The daily human need for digestible carbohydrates averages 365 g (of which 15 ... 20% should be sugar), dietary fiber - 30 g. With a lack of carbohydrates in food, the body consumes its own fats as an energy substance, and then proteins, while the person is losing weight. With an excess of carbohydrates in food, the human body easily turns them into fats and the person becomes stout.

The amount of carbohydrates in food products is different: in potatoes - an average of 16.3, fresh vegetables - 8, cereals - 70, rye bread - 45, milk - 4.7%.

pectin substances. These substances are derivatives of carbohydrates and are part of vegetables and fruits. These include protopectin, pectin, pectic and pectic acids. These substances are like alimentary fiber stimulate the process of digestion and promote the removal of harmful substances from the body.

Protopectin is part of the intercellular plates that connect cells to each other. It is abundant in unripe fruits and vegetables, during the ripening of which protopectin passes into pectin under the action of enzymes, which leads to softening of fruits and vegetables. When heated with water or dilute acids, protopectin also turns into pectin. This explains the softening of vegetables and fruits during heat treatment.

Pectin soluble in water, found in the cell sap of fruits and vegetables. When boiled with sugar (65%) and acids (1%), it is able to form a jelly. This property of pectin is used in the production of marmalade, jelly, jam, preserves, marshmallows, etc.

pectin and pectic acid are formed from pectin under the action of enzymes during the ripening of fruits, giving them a sour taste.

Apples, apricots, plums, cherry plums, black currants are rich in pectins. On average, they contain 0.01 ... 2% pectin.

FATS

Fats are esters of the trihydric alcohol glycerol and fatty acids. They are of great importance for human nutrition. Fats perform a number of important functions in the human body. Fats are involved in almost all vital metabolic processes in the body and affect the intensity of many physiological reactions - the synthesis of protein, carbohydrates, vitamin D, hormones, as well as the growth and resistance of the body to diseases. Fats protect the body from cooling, are involved in the construction of tissues. Like carbohydrates, fats serve as a source of energy (reimbursing 30% of a person's energy expenditure per day) and fat-soluble vitamins.

The nutritional value of fats and their properties depend on their constituent fatty acids, of which about 70 are known. fatty acids subdivided into saturated (limiting), i.e., saturated to the limit with hydrogen, and unsaturated (unsaturated), having double unsaturated bonds in their composition, so they can attach other atoms.

The most common saturated fatty acids are palmitic (C 15 H 31 - COOH) and stearic (C 17 H 35 -COOH). These acids are found mainly in animal fats (lamb, beef).

The most common unsaturated fatty acids include oleic (C 17 H 33 -COOH), linoleic (C 17 H 31 -COOH), linolenic (Ci 7 H 29 - COOH) and arachidonic (C 19 H 31 - - COOH). They are found predominantly in vegetable fats, as well as in pork, fish oil. The biological value of linoleic, linolenic and arachidonic fatty acids is equal to vitamin F, they are called polyunsaturated fatty acids. In the human body, they are not synthesized and must be supplied with dietary fats.

The chemical composition of fatty acids affects the consistency of the fat in which they are included. Depending on this, fats at room temperature are solid, ointment-like, liquid. The more saturated fatty acids in the composition of fats, the higher their melting point, such fats are called refractory. Fats, which are dominated by unsaturated fatty acids, are characterized by a low melting point, they are called fusible. The melting point of lamb fat is 44...51 °C, pork - 33...46 "C, cow oil - 28...34 °C, sunflower oil - 16...19 "C. The digestibility of fats in the body depends on the melting point of fats. Refractory fats are absorbed by the body worse, since their melting point is higher than the temperature of the human body, they are suitable for food only after hot heat treatment. Low-melting fats can be used without heat treatment (butter and sunflower oils).

By origin, animal fats are distinguished, obtained from the adipose tissue of animal products, and vegetable fats - from seeds of plants and fruits.

Fats do not dissolve in water, but soluble in organic solvents(kerosene, gasoline, ether), which is used in the extraction of vegetable oil from sunflower seeds.

fats with water can form emulsions i.e., distributed in water in the form of tiny balls. This property of fat is used in the food industry in the production of mayonnaise, margarine.

During storage, especially under the influence of light and elevated temperature, fats are oxidized(rancid) with atmospheric oxygen, acquiring an unpleasant taste and smell. Fats containing unsaturated fatty acids go rancid most quickly.

Fats, which include unsaturated fatty acids, under certain conditions, can add hydrogen. The process of adding hydrogen to fats is called hydrogenation. As a result, liquid fats turn into solid ones. They are called salomas and are used as a base in the production of margarine and cooking oils.

At high temperatures during frying, fats smoke with the formation of the toxic substance acrolein. For frying, fats with a high smoke point (160 ... 190 ° C) should be used, for example, pork melted fat, sunflower oil, cooking oils.

Under the action of water, high temperature, acids, alkalis and enzymes, fats hydrolyzed those. break down to form fatty acids and glycerol. This process occurs during intense boiling of meat broths. The fatty acids obtained as a result of hydrolysis give the broth a cloudy, greasy taste and an unpleasant odor. In the human body, during digestion, fats are hydrolyzed by the enzyme lipase.

natural fats contain fat-like substances - phos-fatides (in the form of lecithin, cephalin) and sterols (in the form of cholesterol, ergosterol), as well as fat-soluble vitamins (A, D and E) and aromatic compounds, which increases their nutritional value.

The energy value of 1 g of fat is 9 kcal.

Fats significantly improve the taste of dishes, contribute to uniform heating of food during frying. By dissolving the coloring and aromatic substances of vegetables during frying and sautéing, fats give the dishes color and aroma. Distributed throughout the mass of the product, fats contribute to the formation of a particularly delicate structure, which improves the organoleptic properties and increases the overall nutritional value of the food.

Average daily physiological norm fat consumption is 83 g, of which 30% should be vegetable oils - sources of unsaturated fatty acids and 20% - butter - easily digestible, rich in vitamins.

Fats are found in almost all products, but in different quantities: in meat they are 1 ... 49%, fish - 0.5 ... 30%, milk - 3.2%, butter - 82.5%, sunflower oil - 99,9 %.

PROTEINS

Squirrels- it's complicated organic compounds, which include carbon, hydrogen, oxygen, nitrogen; phosphorus, sulfur, iron and other elements may also be included. These are the most important biological substances of living organisms. They are the main material from which human cells, tissues and organs are built. Proteins can serve as a source of energy, covering 12% of the total human energy requirement, and form the basis of hormones and enzymes that contribute to the basic manifestations of life (digestion, growth, reproduction, etc.).

Proteins are made up of amino acids, interconnected in long chains. Currently, more than 150 natural amino acids are known. About 20 of them are found in foods. In the human body, food protein is broken down into amino acids, from which proteins characteristic of humans are then synthesized. Amino acids contained in proteins, according to their biological value, are divided into interchangeable and irreplaceable.

Interchangeable amino acids (arginine, cystine, tyrosine, alanine, serine, etc.) can be synthesized in the body from other amino acids found in food. Essential amino acids cannot be synthesized by the body and must be obtained from food.

indispensable eight amino acids - methionine, tryptophan, lysine, leucine, phenylalanine, isoleucine, valine, threonine. The most scarce and valuable are methionine, tryptophan and lysine contained in animal food.

Depending on composition Proteins are conventionally divided into two groups - simple (proteins) and complex (proteins).

Simple proteins are made up of only amino acids. These include albumins (found in milk, eggs), globulins (in meat, eggs), glutenins (in wheat).

Complex proteins consist of simple proteins and a non-protein part (carbohydrates, phosphatides, dyes, etc.). The most common complex proteins are milk casein, egg vitellin, etc.

Origin Proteins are both animal and vegetable. Animal proteins are mostly complete, especially proteins of milk, eggs, meat, fish. vegetable proteins are incomplete, with the exception of rice and soy proteins. The combination of animal and vegetable proteins increases the value of protein nutrition.

Proteins have certain properties. heating, ultrasound, high pressure, ultraviolet radiation and chemicals can cause denaturation(coagulation) of proteins, in which they condense and lose their ability to bind water. This explains the loss of moisture in meat and fish during heat treatment, which leads to a decrease in the mass of the finished product.

Milk protein - casein - denatures under the action of lactic acid during lactic acid fermentation, which is the basis for the preparation of fermented milk products. The formation of foam on the surface of broths, fried meat and fish products is also explained by the coagulation of soluble proteins (albumin, globulin).

Denatured proteins do not dissolve in water, lose their ability to swell, and are better digested in the human body.

Incomplete protein - meat and fish collagen - is insoluble in water, diluted acids and alkalis, and when heated with water forms glutin, which solidifies when cooled, forming a jelly. The preparation of aspic dishes and jellies is based on this property.

Under the action of enzymes, acids and alkalis, proteins hydrolyzed to amino acids with the formation of a number of intermediate products. This process occurs in the manufacture of sauces on meat broths seasoned with tomato or vinegar.

Proteins are capable to swell, what can be seen when making dough, and when whipping - form foam. This property is used in the manufacture of puddings, mousses, sambuca. Under the action of putrefactive microbes, proteins undergo rotting with the formation of ammonia (NH 3) and hydrogen sulfide (H 2 S).

The energy value of 1 g of protein is 4 kcal.

The average daily physiological need of a person for proteins is 75 g, and proteins of animal origin, as complete ones, should be 55% of the daily norm.

In human nutrition, the balance of essential nutrients is very important. The ratio of proteins, fats and carbohydrates for the main population groups is considered to be optimal in nutrition as 1:1.1:4.

Currently, scientists around the world are working on the problems of creating synthetic food. Of the three main nutrients (proteins, fats, carbohydrates), protein synthesis is of particular interest, since the need to find additional resources for its production is caused by relative protein starvation on our planet. This problem is solved by the chemical synthesis of individual amino acids and the production of protein for animal husbandry with the help of microbes.

VITAMINS

vitamins are low molecular weight organic compounds of various chemical nature. They play the role of biological regulators of the chemical reactions of metabolism occurring in the human body, participate in the formation of enzymes and tissues, and support the protective properties of the body in the fight against infections.

The assumption about the existence of special substances in products was expressed in 1880 by the Russian doctor N.I. Lunin. The Polish scientist K. Funk in 1911 isolated in pure form from rice bran a substance containing the amine group NH 2, which he gave the name "vitamin" (vital amine). A great contribution to the study of vitamins was made by teams of domestic scientists led by B. A. Lavrov, A. V. Palladin.

Currently, several dozens of substances have been discovered that, according to their effect on the human body, can be attributed to vitamins, but 30 of them are of direct importance for nutrition. Many vitamins are designated by letters of the Latin alphabet: A, B, C, D, etc. In addition, each of them has a name corresponding to the chemical structure. For example, vitamin C vitamin C, vitamin D - calciferol, vitamin B) - thiamine, etc.

Vitamins, as a rule, are not synthesized by the human body, so the main source of most of them is food, and more recently synthesized vitamin preparations. Some vitamins can be synthesized in the body (B 2 , B 6 , B 9 , K and PP). The daily requirement of the human body for vitamins is calculated in milligrams.

Lack of vitamins in food causes diseases - beriberi. Insufficient intake of vitamins causes hypovitaminosis, and excessive intake of fat-soluble vitamins in the form of pharmaceutical preparations - hypervitaminosis.

Vitamins are found in almost all foods. Some products are fortified during the production process: milk, butter, flour, products baby food, confectionery, etc.

Depending on the solubility, vitamins are divided into water-soluble - group B, C, H, P, PP, choline and fat-soluble - A, D, E and K. Vitamin-like substances include vitamins F and U.

Water soluble vitamins. The vitamins of this group include B, B 2, B 6, B 9, B 12, B 15, C, H, P, PP, choline, etc.

Vitamin B [thiamine) plays an important role in metabolism, especially in carbohydrate metabolism, in regulating the activity of the nervous system. With a lack of this vitamin in food, disorders of the nervous system and intestines are observed. The lack of a vitamin in the diet leads to beriberi - a disease of the nervous system "take-take". The daily intake of the vitamin is 1.5 mg. This vitamin is found in plant and animal foods, especially in yeast, wheat bread of the 2nd grade, peas, buckwheat, pork, and liver. The vitamin is resistant to heat treatment, but is destroyed in an alkaline environment.

Vitamin B2 [riboflavin] takes part in the growth process, in protein, fat and carbohydrate metabolism, normalizes vision. With a lack of vitamin B 2 in food, the condition of the skin, mucous membrane, vision worsens and the function of gastric secretion decreases. The daily intake of the vitamin is 1.8 mg. This vitamin is found in eggs, cheese, milk, meat, fish, bread, buckwheat, vegetables and fruits, yeast. During heat treatment, it is not destroyed. Vitamin loss occurs when foods are frozen, thawed, dried and stored in the light.

Vitamin B 6 [pyridoxine] takes part in metabolism. With its lack of nutrition, a disorder of the nervous system, dermatitis ( skin diseases), sclerotic changes in the vessels. The daily intake of vitamin is 1.8 ... 2.2 mg. The content of vitamin B 6 in many foods is low, but human needs can be met with a properly balanced diet. The vitamin is resistant to cooking.

Vitamin B 9 [ folic acid) provides normal hematopoiesis in the human body and is involved in metabolism. With a lack of folic acid in the diet, people develop various forms of anemia. The daily intake of the vitamin is 0.2 mg. Properly balanced daily rations contain 50...60% of the daily requirement of vitamin B 9 . The missing amount is supplemented by the synthesis of the vitamin by intestinal bacteria. A lot of this vitamin is found in green leaves (lettuce, spinach, parsley, green onions). Vitamin is very unstable to heat treatment.

Vitamin B p [cobalamin), like folic acid, it plays an important role in the regulation of hematopoiesis, in the metabolism of proteins, fats and carbohydrates. With a lack of vitamin B 12, the body develops malignant anemia. The daily intake of the vitamin is 0.003 mg. This vitamin is found only in products of animal origin: in meat, liver, milk, cheese, eggs. The vitamin is resistant to cooking.

Vitamin B 15 (pangamic acid) participates in the oxidative processes of the body, having a beneficial effect on the heart, blood vessels, blood circulation, especially in old age. The daily intake of the vitamin is 2 mg. It is found in rice bran, yeast, liver and blood of animals.

Vitamin C (ascorbic acid) plays an important role in the redox processes of the body, affects protein, carbohydrate and cholesterol metabolism. The lack of vitamin C in the diet reduces the human body's resistance to various diseases. Its absence causes scurvy. The daily intake of vitamin is 70 ... 100 mg.

Vitamin C is contained mainly in fresh vegetables and fruits, especially a lot of it in rose hips, black currants and red peppers, it is also found in parsley and dill, green onions, white cabbage, red tomatoes, apples, potatoes, etc. Potatoes, fresh and sauerkraut, although they contain little of this vitamin, are an important source of it, since these products are consumed almost daily.

Vitamin C is unstable during cooking and storage of foods. The vitamin is detrimental to light, air, high temperature, water in which it dissolves, oxidizing parts of the equipment. It is well preserved in an acidic environment (sauerkraut). In the process of cooking, factors that negatively affect the preservation of the vitamin should be taken into account: for example, it is impossible to store peeled vegetables in water for a long time. When cooking, vegetables should be poured with hot water, completely immersing them, cook with the lid closed with a uniform boil, avoiding overcooking. For cold dishes, vegetables should be cooked unpeeled. Vitamin C is destroyed when rubbing boiled vegetables, when reheated vegetable dishes and their long-term storage.

Vitamin H (biotype) regulates the activity of the nervous system. With a lack of this vitamin in the diet, nervous disorders with skin lesions are noted. The daily intake of vitamin is 0.15 ... 0.3 mg. It is partially synthesized by intestinal bacteria. In products, biotin is present in small quantities (in the liver, meat, milk, potatoes, etc.). The vitamin is resistant to cooking.

Vitamin P (bioflavonoid) has a capillary-strengthening effect and reduces the permeability of the walls blood vessels. He contributes better assimilation vitamin C. The daily intake of the vitamin is 35 ... 50 mg. This vitamin is found in sufficient quantities in the same plant foods that contain vitamin C.

Vitamin PP (nicotinic acid) is an integral part of some enzymes involved in metabolism. Lack of vitamin PP in food causes fatigue, weakness, irritability and the disease "pellagra" (rough skin), which is characterized by a disorder of the nervous system and skin disease. The daily intake of the vitamin is 20 mg. Vitamin PP can be synthesized in the human body from an amino acid (tryptophan). This vitamin is found in foods of plant and animal origin: bread, potatoes, carrots, buckwheat and oatmeal, beef liver and cheese. With a varied diet, a person receives a sufficient amount of this vitamin. During cooking, vitamin loss is negligible.

Choline affects protein and fat metabolism, neutralizes substances harmful to the body. The absence of choline in food contributes to fatty degeneration of the liver, kidney damage. The daily intake of vitamin is 500 ... 1,000 mg. Choline is found in animal and vegetable products (except vegetables and fruits): in the liver, meat, egg yolk, milk, grains and rice.

fat soluble vitamins. Vitamin A (retinol) affects the growth and development of the skeleton, vision, the condition of the skin and mucous membranes, the body's resistance to infectious diseases. With a lack of vitamin A, growth stops, hair falls out, the body is depleted, visual acuity is dulled, especially at dusk (“ night blindness"). The daily intake of the vitamin is 1 mg.

Vitamin A is found in animal products: fish oil, liver, eggs, milk, meat. Vegetable products of yellow-orange color and green parts of plants (spinach, lettuce) contain provitamin A - carotene, which in the human body in the presence of food fat turns into vitamin A. The need for vitamin A is met by 75% due to carotene. The daily intake of carotene is 3 ... 5 mg.

Vitamin A and carotene are resistant to cooking. Carotene dissolves well in fats when sautéing vegetables. Detrimental to vitamin A sunlight, atmospheric oxygen and acids.

Vitamin D (calciferol) participates in the formation of bone tissue, promotes the retention of calcium and phosphorus salts in it, stimulates growth. With a lack of this vitamin in the body of children develops serious disease"rickets", and in adults they change bone tissue. The daily intake of the vitamin is 0.0025 mg. Vitamin D is found in animal foods: in cod liver, halibut, herring, cod, beef liver, butter, eggs, milk, etc. But it is mainly synthesized in the body, formed from provitamin (a substance found in the skin) as a result of exposure ultraviolet rays. Adults under normal conditions do not lack this vitamin. Excess intake of vitamin D (in the form of pharmaceutical preparations) can lead to poisoning.

Vitamin E (tocopherol) affects the reproduction process. With a lack of this vitamin, changes occur in the human reproductive and central nervous systems, the activity of the glands is disrupted. internal secretion. The daily intake of the vitamin is 10 mg. Vitamin E is found in both plant and animal products, so a person does not experience a lack of it. It is especially abundant in cereal germs and vegetable oils. The content of vitamin in foods decreases when heated. Vitamin E has an antioxidant effect and is widely used in the food industry to slow down the oxidation of fats.

Vitamin K (phylloquinone) participates in the process of blood clotting. With a lack of it, blood coagulation slows down and subcutaneous intramuscular hemorrhages appear. The daily intake of the vitamin is 2 mg. The vitamin is synthesized by bacteria in the human intestine. Vitamin K is mainly found in green lettuce, cabbage, spinach, nettle. It is destroyed by light, heat and alkalis.

Vitamin-like substances. The most important of them are vitamins F and U.

Vitamin F (unsaturated fatty acids: linoleic, linolenic, arachidonic) participates in fat and cholesterol metabolism. The daily intake of the vitamin is 5 ... 8 g. The best ratio of unsaturated fatty acids in lard, peanut and olive oils.

VitaminU (methylmethionine) normalizes the secretory function of the digestive glands and promotes the healing of gastric and duodenal ulcers. Contains vitamin in the juice of fresh cabbage.

ENZYMES

Enzymes(enzymes) are biological catalysts of a protein nature that have the ability to activate various chemical reactions that occur in a living organism.

Enzymes are formed in any living cell and can be active outside of it.

About 1,000 enzymes are known, and each of them has an exceptional specificity of action, that is, it catalyzes only one specific reaction. Therefore, the name of enzymes consists of the name of the substance on which they act, and the ending "aza". For example, the enzyme that breaks down sucrose is called sucrose, enzyme that breaks down lactose lactase.

Enzymes are very active. A tiny dose is enough to transform huge amount substances from one state to another. So, 1.6 g of amylase digestive juice a person in 1 hour can break down 175 kg of starch, air pepsin of gastric juice - 50 kg of egg white.

Enzymes have certain properties. So, some enzymatic processes are reversible, i.e., depending on the conditions, the same enzymes can accelerate both the process of decomposition and the process of synthesis of a substance.

Enzymes are very sensitive to temperature changes. They show the highest activity at 40 ... 50 "C. Therefore, to prevent spoilage of products from the action of enzymes, they are stored in the cold or subjected to heat treatment.

The activity of enzymes depends on the humidity of the environment, an increase in which leads to an acceleration of enzymatic processes, and this leads to spoilage of products. It also depends on the reaction of the medium (pH). So, pepsin of gastric juice acts only in an acidic environment. The rate of enzymatic processes also depends on the state of the substance on which the enzyme acts, and on the presence of other substances in the environment. Thus, meat protein curtailed during heat treatment is broken down by the enzyme faster than raw protein, and the presence of sautéed flour in soups slows down the destruction of vitamin C under the action of enzymes.

Enzymes play an important role in food production, storage and cooking. Rennet enzymes are used in the production of cheeses, enzymes secreted by bacteria and yeast are involved in the production of fermented milk products, fermented vegetables and the fermentation of dough.

Enzymes have a great influence on the quality of products. In some cases, this effect is positive, for example, during the ripening of meat after slaughter of animals and during salting of herring, in other cases it is negative, for example, darkening of apples, potatoes during cleaning, slicing. To prevent browning, apples should be immediately sent to heat treatment, and potatoes should be immersed in cold water. Enzymes destroy vitamin C, oxidizing it during storage and improper cooking of vegetables and fruits, which should be immersed in boiling water or broth during cooking, in which the enzymes are quickly destroyed. Fats are oxidized under the action of enzymes. Souring of soups, rotting of fruits, fermentation of compotes and jams are caused by enzymes secreted by microbes that have got into food. The negative effect of enzymes can be stopped by raising or lowering the air temperature during storage of products.

Currently, scientists are doing a lot of work on the study of enzymatic processes and their further application in the food industry. Methods have been developed for softening the connective tissue of meat with the help of the enzyme prototerrizin, and enzymatic processes that slow down the staleness of bread are being studied.

Enzyme preparations are used in medicine, animal husbandry, in the processing of agricultural raw materials. Enzymes are obtained from cultures of microorganisms, as well as from plant and animal raw materials.

The need for proteins is satisfied by bread, milk, meat, fish, eggs, cottage cheese, cheeses, cereals.

The same products contain energy carriers - carbohydrates and fats, as well as various vitamins and minerals.

Polyunsaturated fatty acids and fat-soluble vitamins are found in vegetable oil.

Fruits and vegetables, including potatoes, are the main "suppliers" of vitamin C, and also have significant amounts of minerals.

The latter, in addition, is rich in starch - also a source of energy.

Brief description of the main food products

Bread

Fats (more precisely, lipids) of bread consist of fats themselves (triglycerides), phospholipids (an essential component of all cells of the body, but especially necessary for the normal functioning of the cells of the nervous system and liver) and sterols (they prevent the absorption of cholesterol into the blood and thus contribute to the prevention atherosclerosis). Of the fatty acids that make up bread lipids, the main ones are linoleic (33-54%), palmitic (10-24%) and oleic (10-24%). The last two fatty acids perform an energy function in the body. However, the total amount of both lipids and their fractions in bread is relatively small.

Carbohydrates in bread are represented mainly by starch, which is broken down into glucose molecules in the gastrointestinal tract by a number of digestive enzymes.

This product is rich in B vitamins, which are part of the so-called water-soluble vitamins: thiamine (B1), riboflavin (B2), pyridoxine (B6), niacin (PP), folacin. At the expense of bread, we usually satisfy a significant part of the daily requirement for these substances.

Bread also contains a significant amount of minerals (chlorine, sodium, potassium, phosphorus, sulfur, magnesium), including trace elements (iron, manganese, zinc, copper, fluorine, molybdenum, iodine, chromium, cobalt).

It contains vegetable fibers, which are shells of plant cells, consisting of cellulose or hemicellulose, which are not digested in the digestive tract, but play an important physiological role contributing to the normal functioning of the intestines.

The so-called black bread baked from rye flour differs from white bread made from wheat flour by a slightly higher content of lysine (i.e. higher biological value) and an increased amount of plant fibers.

The chemical composition of the product in to a large extent depends on the quality of flour grinding. Whole wheat flour baking has more grey colour, contains a significant amount of plant fibers, vitamins and minerals.

In general, bread plays a significant role in our diet. In tsarist Russia, it was the main source of food for the broad masses of the people, and above all for the peasants. They ate it in large quantities - 1.5-2 kg per day, thereby providing the body's basic need for protein, energy (due to starch), water-soluble vitamins and minerals. However, to get the required amount of lysine, it was necessary to consume as part of bread excess amount other amino acids that put an excessive burden on the liver and kidneys. After the Great October Socialist Revolution, the consumption of bread by the population of the USSR has been steadily declining due to an increase in other products, and above all those that contain increased quantities lysine: milk, meat, fish, eggs. At present, bread consumption in our country averages 380 g per person per day. In accordance with the recommended set of food products developed by the Institute of Nutrition, it should be reduced to approximately 300 grams per day.

Milk and dairy products

Milk, according to the famous Russian physiologist I.P. Pavlova, is a highly valuable food product created by nature itself and containing most of the components necessary for a person.

It is an excellent food for a person, but not ideal (that is, it does not contain all the substances necessary for the body).

Milk proteins (2.8-2.9%), unlike bread proteins, are complete - they contain a sufficient amount of all essential amino acids - the same or higher than in an ideal protein. It is interesting to note that such a severely scarce essential acid, like lysine, there is much more in milk than in ideal protein, and if you drink milk, eating it with bread, then the proteins of the latter are enriched at the expense of milk proteins.

This food product is relatively rich in fat (lipids), which is well absorbed: in its natural form it is from 2.9 to 3.6%, on sale it is usually 3.2; 3.5 or 6% (due to the addition of fat). Milk lipids include fats (triglycerides, diglycerides and monoglycerides), phospholipids and sterols. The main fatty acids in the composition of total milk lipids are oleic (23-27%), palmitic (19-33%), myristic (12-15%) and stearic (10-12%); the share of linoleic acid accounts for only 2.4-2.6%. Milk lipids also contain a significant amount of the so-called midrenal fatty acids, which are most easily absorbed from the cavity of the small intestine into the internal environment of the body. They are especially important for the nutrition of newborns with an immature digestive system.

A number of dairy products are prepared from milk, especially rich in fat: cream containing 10 or 20% of it, sour cream - 30%, and finally butter, which is practically milk fat obtained in its pure form.

The carbohydrate component of milk is mainly lactose - milk sugar. In the human digestive tract, it is rapidly broken down.

Milk is rich in vitamins, especially in the summer-autumn period: these are vitamin C, thiamine, riboflavin, vitamin B6, niacin, pantothenic acid, biotin, vitamins B12, A, D and relatively large amounts of folacin and vitamin E.

At the expense of milk and dairy products, a significant proportion of our need for minerals is satisfied. It contains especially a lot of calcium (about 120 mg per 100 g) and potassium (about 150 mg per 100 g). Note that there is little calcium in bread, and therefore it is advisable to use bread with milk to satisfy the body's need for this substance. Milk also contains chlorine, phosphorus, sodium, sulfur, magnesium, zinc, iron, fluorine, iodine, copper, manganese, molybdenum, chromium, selenium, cobalt.

Fermented milk products - kefir, acidophilus, curdled milk, fermented baked milk, obtained as a result of the reproduction of various fungi, have high nutritional and biological value. Of particular note is koumiss, made from mare's milk: it is a natural antibiotic and helps with a number of diseases, including tuberculosis.

When milk is soured, the soluble proteins present in it - caseins undergo denaturation, that is, they lose their natural properties and precipitate in the form of loose flakes. They become more accessible to the action of digestive enzymes and are easier to digest in the gastrointestinal tract. (Milk an hour after eating is absorbed by 32%, and kefir and yogurt - by 91%). The beneficial properties of fermented milk products should also include the fact that lactic acid bacteria contained in them in large quantities are antagonists of putrefactive microorganisms present in the human large intestine and, in the course of their vital activity, secrete a number toxic substances. That is why the consumption of fermented milk products helps to normalize the flora of the human large intestine and reduce the proportion of putrefactive microorganisms in it. The action of lactic acid bacteria was first discovered by the famous Russian scientist I.I. Mechnikov, and then it was confirmed by the work of numerous researchers.

Products with high nutritional and biological value are also cottage cheese and cheeses.

Cottage cheese, as it were, concentrated all the valuable components of milk: it contains a large amount of complete proteins (14%), rich in milk fat (18%), vitamins and minerals, especially calcium.

Cheeses are obtained from milk, previously subjected to curdling with a special enzyme - rennin (or chymosin), present in the abomasum of young calves and lambs. They are rich in complete proteins (23-30%), fats (15-30%), vitamins and minerals. It is a food product containing in a concentrated form a significant part of the important components.

Thus, milk and dairy products are an important part of the daily human diet. They satisfy a significant part of our need for proteins, fats, vitamins, minerals and, to a lesser extent, carbohydrates.

Meat and meat products

Meat (beef, lamb, pork, chickens, ducks, geese, turkeys) is primarily a carrier of high-value proteins, which make up 12-22% and contain all the essential amino acids in greater quantities than an ideal protein.

Meat usually contains some organic lipids, mostly in the form of its own fat. In beef, lamb and pork, the main fatty acids are oleic, palmitic, stearic and, to a lesser extent, linoleic; ducks and geese have more unsaturated fatty acids, including oleic and linoleic.

Carbohydrates in meat are present in very small amounts in the form of glycogen. In my own way chemical structure it is close to plant starch and when it is broken down in the digestive tract under the action of amylolytic enzymes, glucose molecules are ultimately formed, which are absorbed into the blood.

Meat also contains some vitamins (niacin, biotin, vitamin B12, pyridoxine, thiamine, riboflavin, folacin and pantothenic acid), as well as minerals (potassium, sulfur, phosphorus, sodium, chlorine, magnesium, calcium), including trace elements ( zinc, iron, copper, fluorine, tin, manganese, chromium, molybdenum, nickel, cobalt, iodine).

Fish and fish products

Fish, like meat, is primarily a source of high-value proteins; in various species of fish they are from 13 to 20%. The content of all essential amino acids in fish proteins is higher than in an ideal protein. In some types of fish, there is little fat (for example, in haddock - 0.2%), while in others it is significant (for example, in Siberian sterlet - 30.8%). The fatty acid composition of fish fats is different than in meat and milk. In addition to saturated stearic and palmitic acids, as well as oleic acid, they contain a wide range of polyunsaturated fatty acids: linoleic (up to 7%), linolenic (up to 3%), arachidonic (up to 4.5%), fatty acids with five and six double bonds in a carbon chain of 20 or 22 carbon atoms. Some types of fish (for example, herring) contain significant amounts of fat-soluble vitamins (A, D, and E) as well as vitamin B12. High content of potassium, sulfur and phosphorus. Most fish species contain relatively large amounts of trace elements: zinc, iron, copper, manganese, fluorine, iodine, cobalt, nickel.

Eggs

It is a highly valued food product. Their proteins (12.7%) contain all essential amino acids in sufficient quantities. Moreover, in terms of their amino acid composition, they are closer to the ideal than any other natural proteins.

Eggs contain a significant amount of lipids - 11.5%, of which fats (triglycerides) account for 7.45%, phospholipids (mainly lecithin) - 3.39% and cholesterol - 0.57%. Carbohydrates make up only 0.7%.

Both fat-soluble vitamins A, D, E and water-soluble vitamins B12, biotin, folacin, etc. are present here in considerable quantities. However, along with biotin, eggs also contain the antivitamin avidin, an antagonist of biotin.

Eggs are relatively high in phosphorus, sulphur, sodium and potassium and relatively low in calcium and magnesium. Of the trace elements in eggs, iron and zinc are present in significant quantities, while the content of copper, fluorine, manganese, iodine, cobalt, molybdenum and chromium is low.

Eggs contain the so-called trypsin inhibitor (omomucoid), which combines with trypsin in the human intestine and thereby makes it inactive - it suppresses this enzyme. When eggs are boiled, the trypsin inhibitor they contain is converted into normal dietary protein. At the same time, avidin is also destroyed. Therefore, food intake raw eggs should be limited. In general, even boiled eggs should not be eaten more than 7-10 pieces per week; they contain a relatively high amount of cholesterol. In this case, as in the whole food system as a whole, it is necessary to adhere to the principle: nothing is too much.

Potato

Sometimes it is called the second bread, although biologically and nutritional value he is significantly inferior to him. Proteins in it are only 2%, and in terms of amino acid composition they are close to legume proteins.

The amount of lipids in potatoes is very small - 0.4%, and the share of fats themselves (triglycerides) accounts for 0.014%, while 0.34% are phospholipids and glycolipids. The main fatty acids in potato lipids are oleic (48%), linoleic (24%) and palmitic (21%).

Carbohydrates in potatoes are 19.7% and 18.2% of them are starch. Potatoes contain small amounts of sucrose, glucose, fructose, cellulose, pectin and hemicelluloses, as well as malic, citric and oxalic acids.

Potatoes are rich in vitamin C (20 mg per 100 g of edible part of the product); it has less niacin, pantothenic acid, vitamin B6, thiamine, riboflavin, folacin and vitamin E.

Potatoes are very rich in potassium (568 mg per 100 g of product), while they contain an order of magnitude less chlorine, phosphorus, sulfur, sodium, magnesium and calcium. Microelements are widely represented in potatoes (named in descending order): iron, aluminum, rubidium, zinc, manganese, iodine, cobalt, nickel.

Vegetables

These are primarily carriers of vitamins, minerals and plant fibers (cellulose and hemicellulose). The content of proteins, lipids and starch in vegetables is small, and therefore they have a rather low energy value. At the same time, they are rich in vitamins and especially vitamin C, folacin, beta-carotene (a precursor of vitamin A). Vitamin C is most abundant in various varieties of pepper (150-250 mg per 100 g of edible part of the product), parsley (150 mg), dill (100 mg), cabbage (120 mg in Brussels sprouts, 70 mg in cauliflower, 45-60 mg in white). AT winter time We satisfy a significant proportion of the daily requirement for vitamin C with cabbage, especially sauerkraut - the decrease in the amount of vitamin C during storage occurs more slowly in it than in other foods, where it is very significant. Folacin is most in parsley (110 mcg per 100 g of the edible part of the product), less in spinach (80 mcg) and lettuce (48 mcg). Beta-carotene is most found in carrots (9 mg per 100 g of product), wild garlic (4.2 mg), garlic (2.4 mg), onions (2 mg), red pepper (2 mg), lettuce (1.75 mg ), parsley (1.7 mg). Vegetables contain a lot of potassium and 1-2 orders of magnitude less sodium. As for trace elements, vegetables are the richest in iron, zinc, aluminum, manganese and copper. All vegetables contain a significant amount of cellulose, hemicelluloses and pectin - this applies to cabbage, carrots and beets.

Fruits and berries

By their nutritional value, they are close to vegetables: they also contain a very small amount of proteins and lipids and are predominantly carriers of vitamins, minerals and plant fibers. However, unlike most vegetables, fruits contain a significant amount of digestible carbohydrates in the form of mono- and disaccharides, and most often in the form of fructose. In general, fruits and berries contain even more vitamin C than vegetables. For example, in rose hips it is 470 mg per 100 g of product, in blackcurrant - 200, in sea buckthorn - 200, in strawberries - 60, in orange - 60 mg. In fruits and berries, as well as in vegetables, potassium can be considered the main mineral element.

Mushrooms

Mushrooms are a very unique food item. They contain from 0.9 to 3.3% of proteins. Proteins of mushrooms, as well as other plant products, are defective, contain an insufficient amount of essential amino acids: isoleucine and valine. Lipids in mushrooms make up 0.3-0.9%. They also contain some carbohydrates in the form of mono- and disaccharides, as well as a significant amount of plant fibers.

Of the vitamins we could name C, niacin, pantothenic acid, to a lesser extent - E, riboflavin, B6 and thiamine. Mushrooms are relatively rich in folacin. The main representative of mineral substances in them is potassium - it is 1-2 orders of magnitude more than sodium. There is more phosphorus here than calcium. Mushrooms have a very high iron content - up to 6.5 mg per 100 g of product. In addition to this trace element, zinc, manganese, copper, fluorine, rubidium, iodine, cobalt, chromium and nickel were also found in mushrooms.

Even a short list of foods, the substances contained in them, gives an idea of ​​how complex the chemical combination of elements in the food we consume is, and how it is even more complex in the complex chemical process called life.

Everything biologically active substances we divide by endogenous(synthesized within the body) and exogenous(coming from the outside in finished form, with food). The former include low molecular weight regulators (adrenaline, ATP, acetylchomine, etc.) and high molecular weight biopolymers (proteins, DNA, RNA, etc.). All of them are part of the body.

But a number of substances - proteins, fats, carbohydrates, vitamins - enter the body with food. They are called exogenous. It is they who restore energy expenditure, carry out plastic functions.

According to the Institute of Nutrition, the daily diet of an adult should contain more than 600 substances, including 17 vitamins and 20 amino acids. And each product has its own chemical composition, which has a certain effect on the body, has a certain biological activity, and performs a particular function. We can say that completely indifferent substances do not exist.

An organism can function normally only if harmony is maintained, a subtle interaction between endogenous and exogenous substances.

The human body can be likened to a microcosm, in which, as in the macrocosm, that is, on the scale of the planet, almost all chemical elements are contained, the amount of which is not indifferent to the organism as a whole. This is the finest ratio of endogenous and exogenous substances and should provide a balanced, rational diet.

That is what it is essential condition increase life expectancy, maintain health. It should be noted that the sources of nutrients, including animal proteins (meat, fish, milk, eggs) are widely interchangeable. For example, in Japan, where the lowest consumption of meat is recorded, the lack of animal proteins is compensated by the highest consumption of fish. In general, protein-calorie deficiency, in particular the lack of meat and other products of animal origin, can be one of the main causes of poor health.

The main components of food products are proteins, carbohydrates, fats, food acids, salts of mineral acids, enzymes, vitamins, water.

Squirrels. Proteins are organic high-molecular compounds, which include 5 elements: N 2, C, O 2, H 2, S. Protein substances are built from amino acids, have 2 groups NH 2 and COOH, the molecules are connected by peptide bonds. The daily requirement for proteins is 100-120 g. Meat and milk are rich in proteins. Properties of proteins that are used in food industries:

1) the ability to hydrate, that is, to absorb and retain moisture. Under normal conditions, proteins are able to retain two to three times the amount of water. Swelling is due to the ability of proteins related to hydrophilic substances to absorb water and, under certain conditions, form solutions called jelly. The property of swelling is used in food technologies: swelling of oilseed proteins in the production of vegetable oil;

2) denaturation, that is, a change in the spatial orientation of the protein molecule. Denaturation is caused by an increase in temperature, mechanical and chemical influences, for example, in sugar beet production, it is necessary to destroy the protoplasm of a beet cell, which consists of proteins heated above 60 0 C, while the protein coagulates and pores open in the cell membrane to ensure the extraction of sucrose (C 12 H 22 O 11) and other dissolved substances from the vacuole into the environment;

3) foaming, that is, the formation of an emulsion in the "liquid-gas" system called foams. Proteins as foaming agents are widely used in the preparation of confectionery (meringue, marshmallows, marshmallows);

4) the ability to hydrolysis, that is, splitting into constituent parts in the presence of acids and enzymes. This ability is used in oil refining.

Fats (lipids). Normalization of fat can be made according to the caloric value of the daily allowance diet, while 1000 kcal provides 35 g of fat. Fats have certain properties that must be taken into account in food technologies, these include:

1) all fats are insoluble in water, but soluble in organic solvents, this property is used in the production of vegetable oils by the extraction method;

2) fats dissolve well in themselves many organic substances, including aromatic ones;

3) when heated under pressure, fats are split into glycerol and the corresponding fatty acids, in the presence of alkali, this reaction proceeds with the formation of glycerol and salts of fatty acids, this property of fats is used in the perfume and sugar industries;

4) fats in the presence of surfactants (emulsifiers) are able to form stable emulsions (production of margarine and mayonnaise);

5) when stored under adverse conditions ( fever, humidity, light) fats under the influence of the lipase enzyme are hydrolyzed into glycerol and free fatty acids, which are oxidized under the influence of oxygen to form products with a bitter taste - rancidity of fats;

6) at high temperatures (250-300 0 C), fats are hydrolyzed into fatty acids and glycerol, which decomposes to a substance with bad smell– acrolein;

7) as a result of hydrogenation (hydrogenation of polyunsaturated fatty acids), fats can pass from liquid

state into a solid - the production of margarine.

Carbohydrates. Natural organic compounds consisting of 3 elements: C, H 2 and O 2. Carbohydrates are formed in the green leaves of plants from carbon dioxide, water under the influence of solar radiation with the participation of a natural photocatalyst - photosynthesis. Carbohydrates are divided into:

1) simple (monosaccharides) - carbohydrates that are not able to hydrolyze to form simpler compounds. These include hexoses: glucose, fructose, arabinose, xylose - are the structural components of complex polysaccharides. In this group, glucose and fructose, which are present in fruits and berries, are important. Industrially, glucose is obtained by acidic and enzymatic hydrolysis of starch. Glucose is fermented by yeast, its sweetness is 70% of the total sweetness of sucrose. Fructose (levulose) is hygroscopic in air, which makes it difficult to use in its pure form. AT aqueous solutions rapidly decomposes, as glucose is fermented by yeast. More than twice as sweet as glucose;

2) complex carbohydrates (di- and polysaccharides), they are able to hydrolyze into simpler ones, their number of carbon atoms is not equal to the number of oxygen atoms. Complex carbohydrates are divided into 2 types:

Low molecular weight (sugar-like or oligosaccharides);

High molecular weight (non-sugar-like).

The first group includes sucrose, maltose, lactose. They have the property of undergoing acid or enzymatic hydrolysis to form two monoses. Sucrose is the most common sugar in the plant world, found in sugar beet, cane, melon and watermelon. Well fermented by yeast, hydrolyzed

C 12 H 22 O 11 + H 2 O → C 6 H 12 O 6 + C 6 H 12 O 6

The mixture of glucose and fructose is called invert sugar.

Maltose breaks down into 2 molecules of glucose during hydrolysis. It is found in cereal seeds, especially during their germination. Maltose is obtained from the enzymatic hydrolysis of starch.

Lactose hydrolyzes into galactose and glucose and is found in milk.

The second group includes starch, cellulose, pectin substances. Starch is the most important polysaccharide in nutritional value. When boiled with dilute acids, it turns into glucose, during enzymatic hydrolysis (malt amylase) maltose and partially glucose are formed. In the food industry, starch is the main raw material for the production of glucose and molasses, which is used in the confectionery industry. Cellulose (fiber) - food carbohydrate, has no practical significance as an energy source, but, although fiber in small intestine almost not absorbed, normal digestion without it is almost impossible. Lack of fiber in the diet contributes to the development of obesity, gallstone disease, cardiovascular disease. Fiber creates favorable conditions for the normal movement of food through gastrointestinal tract. In addition, fiber normalizes the activity of beneficial intestinal microflora, promotes (especially together with pectin contained in vegetables and fruits) the removal of cholesterol from the body. Pectin substances form complex compounds with heavy metals and radionuclides and remove them from the body. In an acidic environment in the presence of sugar and acid, fruit and berry jelly is formed; the production of jams and marshmallows is based on this property of pectin substances.

Nutritional value of carbohydrates. Relative sweetness of sugars in conventional units according to RAMS: sucrose 100%, fructose 173%, glucose 74%, galactose 32.1%, maltose 32.5%, lactose 16%, invert sugar 130%.

Properties of carbohydrates used in food technologies:

1) the ability of simple carbohydrates to be fermented by yeast enzymes (obtaining wine, beer);

2) simple carbohydrates can be obtained by preliminary hydrolysis of polysaccharides (alcohol production);

3) the ability to dissolve in water and crystallize (sugar industry);

4) lack of dissolution properties in water (technology for obtaining pure starch from potatoes);

5) the ability of starch to hydrolysis makes it possible to obtain complete and incomplete hydrolysis products;

6) the ability of pectin substances to form jelly in the presence of sucrose and organic acids (confectionery production).

Enzymes. Enzymes or enzymes are called complex biological catalysts of a protein nature that change the rate of chemical reactions. Enzymes in some cases accelerate technological processes food production, in others they make it difficult.

The transformation of feedstock into finished products in winemaking, brewing, alcohol production, cheese making, baking, technological processes are accelerated. In sugar production, enzymes decompose sucrose - bad influence. Enzymes have a pronounced specific action, for example, invertase breaks down sucrose into glucose and fructose; amylases are a group of enzymes that hydrolyze starch to form dextrins and maltose. The hydrolysis of pectin substances proceeds with the participation of pectolytic enzymes, their use makes it possible to increase the yield of the product and clarify fruit and berry juices.

organic acids. In many cases, taste merits are determined. The daily requirement for them is about 2 g, which is met by fruits and vegetables. Lactic, malic, tartaric, and citric acids predominate in food products.

Minerals. They do not have energy value like proteins, fats and carbohydrates, but without them human life is impossible. Minerals are divided into 2 groups:

1) macronutrients - Ca, P, Mg, Na, K, Cl, S, are found in food in relatively large quantities;

2) microelements - Fe, Zn, Cu, J, F. The content of mineral substances in products is on average 1%: 0.99% - macroelements, 0.01% - microelements.

Vitamins. Vitamins are a group of substances of organic nature that play an extremely important role in the activity of the body, they are necessary for a person to normal exchange substances, tissue growth, protection against disease. The human body does not synthesize vitamins, it must receive them from food. Vitamins are divided into water-soluble: C, H, B and fat-soluble: A, D, E, K. Heat treatment, storage lead to a decrease in their nutritional and vitamin value, for example, when grinding premium flour with bran, 20% of the vitamins contained in the original are lost. raw materials.

Water. The human body is ⅔ water. Approximately 87% of the water a person receives from food and drinks, the remaining 13% are formed as a result of the oxidation of nutrients. Water is an ideal medium in which all processes of synthesis and decay take place, in addition, water itself participates in chemical reactions. The water content in food products fluctuates, for example, in sugar, tea, salt, vegetable oil it is almost absent, in vegetables it is 95%. Humidity, in % of some products:

Flour, grain 12-15%;

Bread 38-48%;

Granulated sugar 0.14%;

Starch 13%;

Fruit 75-90%;

Vegetables 65-95%;

Milk 87-88%;

Butter 14-15%;

Vegetable oil 1%;

Beef meat 54-79%;

Excessive moisture content of foodstuffs contributes to their damage by molds and other harmful microorganisms, activates the action of enzymes that can cause spoilage of the product, and, conversely, the removal of water by drying or freezing allows long-term storage.

The energy value of food products (calorie content) is the amount of energy that is formed during the oxidation of fats, proteins and carbohydrates contained in products and is used for the physiological functions of the body.

Calorie content is an important indicator of the nutritional value of foods, expressed in kilocalories (kcal) or kilojoules (kJ). One kilocalorie is equal to 4.184 kilojoules (kJ), The energy value of proteins is 4.0 kcal / g (16.7 kJ / g). It is usually calculated per 100 g of the edible part of the food product to determine the energy value of the product, you should know its chemical composition.

Food products are characterized by a complex of simple and complex properties- chemical, physical, technological, physiobiological, etc. The combination of these properties determines their usefulness for humans. The usefulness of food products is characterized by nutritional, biological, physiobiological, energy value, good quality and organoleptic properties.

The energy value of the product is the energy that is released from the nutrients of the products in the process of biological oxidation and is used to ensure the physiological functions of the body.

In the process of life, a person expends energy, the amount of which depends on age, the physiological state of the body, the nature of work, climatic conditions, etc. Energy is formed as a result of the oxidation of carbohydrates, fats, proteins contained in the cells of the body, and to a small extent other compounds - acids, ethyl alcohol, etc. Therefore, it is necessary to know the amount of energy consumed per day by a person in order to restore its reserves in a timely manner. The energy that a person spends is manifested in the form of heat, so the amount of energy is expressed in thermal units.

The necessary substances enter the body with food. They are also used to provide the components of cells, tissues and organs, for growth, increase in body weight. Therefore, food should provide optimal conditions for human life and performance.

A sufficient amount of high quality food products in the body allows you to organize a balanced (rational) diet, i.e. organized and timely supply of the body with products that contain all the substances necessary for tissue renewal, energy consumption and are regulators of numerous metabolic processes. At the same time, food substances should be in favorable proportions among themselves. The number of essential components in a balanced diet exceeds 56 items.

A balanced diet requires a certain regimen, i.e. distribution of food intake during the day, maintaining a favorable food temperature, etc. With a balanced human diet, such basic substances as proteins, fats and carbohydrates should be in food in a ratio of 1:1:4; and for people engaged in heavy physical labor, respectively, 1:1:5. The amount of proteins, fats and carbohydrates required for people of different professions with a balanced diet is different. So, for people of professions not related to the use physical labor, the daily requirement is (in g): in proteins - 100, in fats 87, in carbohydrates - 310. for people whose professions are associated with the use of mechanized labor, such a need is 120, 105 and 375 g, respectively, and with the use of non-mechanized labor - 200, 175 and 620

Table

Daily human need for nutrients

15* = 10 mg tocopherol.

100** = 2.5 µg of vitamin D3.

The nature of proteins, fats and carbohydrates is of great importance in human nutrition. It is believed that the total amount of proteins should provide 15% of the daily calorie content (energy value), and of this amount, more than 50% of animal proteins should be accounted for, about 30% of the calorie content of fats (of which 25% are vegetable), the share of carbohydrates is slightly more than 50% (of which 75% for starch, 20% for sugars, 3% for pectins, and 2% for fiber).

The energy costs of a person are the sum of energy consumption for basic metabolism, food intake and labor activity.

The energy expended by the body for basic metabolism is associated with the work of internal organs (heart, lungs, endocrine glands, liver, kidneys, spleen, etc.). It is believed that an adult man weighing 70 kg spends 1700 kcal, or 7123 kJ, on the main metabolism per day, and a woman - 5% less. Older people have lower energy expenditure than younger people.

Eating increases energy consumption for the body's basal metabolism by an average of 10-15% per day and depends on the nature of a person's activities. So, for different types of work, it takes about next quantity energy (kcal/h):

with light physical mechanized work - 75; during work of medium severity, partially mechanized - 100;

with intense physical non-mechanized work - 150-130;

with very hard physical work and sports - 400 or more.

According to energy costs, the adult population of the country is divided into five groups, children - into eight. In addition, the energy costs of men and women aged 18-29, 30-39, 40-59 years are separately distinguished. The elderly are a special group. The energy value of food products is expressed in kcal or kJ (1 kcal corresponds to 4.186 kJ).

In table. data characterizing the energy costs of men and women aged 18 to 60 years for various types of labor are given. When calculating the energy demand for the population at the indicated age, the average body weight was assumed to be 70 kg for men and 60 kg for women.

Table

Characteristics of the energy costs of men and women different ages for various types of work

Until recently, it was believed that the oxidation of 1 g of protein, digestible carbohydrates and organic acids in the human body releases about 4.1 kcal (17.2 kJ), while the oxidation of 1 g of fats 9.3 kcal (38.9 kJ), later it was found that the energy value of carbohydrates is somewhat lower than that of proteins (table).

Table

Energy value coefficients of various nutrients

Fats and carbohydrates normal process assimilation in the body is broken down to end products (carbon dioxide and water), as in normal combustion. Proteins are not completely broken down, with the release of products such as urea, creatinine, uric acid and other nitrogenous compounds with significant potential thermal energy. Therefore, the amount of heat during the complete oxidation of the protein to the final products (ammonia, water and carbon dioxide) is greater than during its oxidation in the body.

The energy value of food can be determined by its chemical composition. So, if pasteurized milk contains (in%): proteins - 2.8, fats - 3.2 and sugars - 4.7, then the energy value of 100 g of milk will be 57.86 kcal (4.0 kcal * 2.8 + 9.0 kcal* 3.2 +3.8 kcal* 4.7), or 241.89 kJ.

If the daily diet contains (in g):

proteins - 80, carbohydrates - 500, fats - 80, then its total energy value will be 2915 kcal (4.0 kcal * 80 +9.0 kcal * 80 + 3.8 kcal * 500), or 12,184.7 kJ.

Depending on the chemical composition, the energy value of food products is different (table).

Table

Energy value of various foods

The highest energy value has: butter, margarine, chocolate, sugar cookies and granulated sugar, low - milk, apples, cabbage, some types of fish (carp, cod, etc.).

Table

Chemical composition of food

Calculation of the energy value of food products

To determine the theoretical calorie content of 100 g of food, you need to know the specific calorie content of nutrients (1 g of fat releases 9 kcal; 1 g of protein - 4.1 kcal; 1 g of carbohydrates - 3.75 kcal) and multiply by the amount contained in the products. The sum of the obtained indicators (products) determines the theoretical calorie content of the food product. Knowing the calorie content of 100 g of the product, you can determine the calorie content of any of its quantities. Knowing the theoretical calorie content, for example, carbohydrates, you can find the practical (actual) calorie content of carbohydrates by multiplying the result of the theoretical calorie content of carbohydrates by digestibility in products (for carbohydrates - 95.6%) and dividing the product by 100.

Calculation example. Determine the theoretical calorie content of 1 cup (200 g) of cow's milk.

According to the table of chemical composition or the textbook of commodity science, we find the average chemical composition of cow's milk (in%):

fat - 3.2; proteins - 3.5; milk sugar - 4.7; ash - 0.7.

Solution:

The calorie content of fats in 100 g of milk is 9x3.2 = 28.8 kcal. The calorie content of proteins in 100 g of milk is 4 x 3.5 = 14.0 kcal. The calorie content of carbohydrates in 100 g of milk is 3.75 x 4.7 \u003d 17.6 kcal.

The theoretical calorie content of 1 glass of milk (200 g) will be equal to 60.4 x 2 = 120.8 kcal (28.8 + 14.0 + 17.6) x 2: The actual caloric content will be, taking into account the digestibility of fat - 94%, proteins - 84.5%, carbohydrates - 95.6%.

17.6*95/100 + 28.8*94/100+ 14.0*84.5/100= 54.73 kcal

To convert kilocalories to kilojoules, the number of kilocalories is multiplied by 4.184 (according to the SI system).

The composition of food products includes inorganic and organic substances.

Inorganic substances include water and minerals, organic substances include proteins, carbohydrates, fats, vitamins, organic acids, enzymes, dyes, pectin, tannins, phytoncides, glycosides, alkaloids.

Food products are a source of energy, a building material and are involved in the regulation of the metabolic process.

Water - takes part in all life processes of a living organism. The water content in the human body is on average 2/3 of body weight. The daily human need for water depends on physical activity, climatic conditions and is 1.5-2 liters. So without food, a person can exist for about a month, while without water - no more than 10 days.

In food products, water can be in the free and bound state. Free water is in the form of tiny droplets on the surface or in the mass of the product. Free water is easily removed during drying and freezing of products.

Bound water is called water, the molecules of which are more or less firmly connected with other substances of the product. Free and bound water during storage and processing can move from one state to another and cause a change in their properties. For example, during the storage of bread, bound water partially passes into a free state, as a result of which it becomes stagnant. Food products with a high water content are unstable in storage, because microorganisms can easily grow in them. The more water in the products, the lower their nutritional value and the shorter their shelf life. In each product, the water content must be certain: an increase in the water content in cookies, cereals, flour, tea causes mold, in jam, honey - fermentation, and its decrease in vegetables, fruits leads to their rapid deterioration.

Certain requirements are imposed on the quality of drinking water. It should be colorless, transparent, odorless, without foreign tastes and harmful trace elements and have the appropriate chemical composition.

Minerals- are part of all cells, tissues, bones; they support acid-base balance in the human body and provide big influence for metabolism. Minerals are divided into micro and macro elements. The macronutrients are sodium, potassium, calcium, magnesium, chlorine, silicon, sulfur, iron and etc. sodium and chlorine found in table salt. Potassium improves heart function. A lot of potassium is found in vegetables. Calcium part of the bones and teeth, found in milk and dairy products, legumes, bread, eggs, vegetables. Magnesium helps to lower cholesterol, has an effect on the nervous system. Peas, oatmeal, rye bread are rich in magnesium. Sulfur found in cereals, bread, meat, cheese, fish; is included in the insulin hubbub. Iron is part of hemoglobin, its deficiency causes a breakdown, anemia. A large amount of iron is found in meat, liver, buckwheat and oatmeal, egg yolk, berries. Phosphorus is part of bones and teeth, participates in nervous tissues, as well as in the process of assimilation of carbohydrates, proteins and fats. Fish, vegetables, cheese, meat, rye bread, eggs, nuts, cereals, dairy products are rich in phosphorus.

To trace elements include substances whose content in products is negligible - these are iodine, zinc, copper, fluorine, bromine, manganese, etc. Iodine necessary for the normal functioning of the thyroid gland. Lots of iodine in seafood walnuts, lettuce, spinach. Manganese participates in the formation of bones, the formation of hemoglobin, the growth of the body. A lot of manganese in leafy vegetables, cereals, bread, fruits. Copper and cobalt are involved in hematopoiesis. They are found in beef liver, fish, and beets. Fluorine needed for the formation of bones and teeth. It is found in milk and meat, in bread made from plain flour. Zinc is part of all tissues, affects the function of the pancreas, fat metabolism, promotes growth young body. Zinc is found in liver, beef, eggs, onion. Zinc in large quantities can lead to poisoning of the body. A person's need for trace elements is expressed in milligrams or fractions of a milligram, but their absence or lack of nutrition leads to serious complications.

Squirrels- the most important biological substances of living organisms. They are the main building material from which human cells, tissues and organs are built. According to their composition, proteins are divided into simple (proteins) and complex (proteins). The daily requirement of an adult in protein is 80-100 grams.

Carbohydrates- found mainly in plant products. An adult needs 400-500 g of carbohydrates per day. Carbohydrates almost entirely consist of sugar, starch, honey, cereals, pasta and other products, they are easily absorbed in the body. With excessive consumption of carbohydrates, they turn into fat in the human body.

Fats is an important part of food products. The importance of fats in human nutrition is primarily due to their high energy capacity. Fats are distinguished by origin: animal, vegetable, combined; Consistency - liquid and solid.

vitamins- irreplaceable substances in human food, necessary for him in small quantities. Lack of vitamins in food leads to a disease called avitaminosis. Vitamins are divided into water-soluble and fat-soluble.

Water soluble: Vitamin C (ascorbic acid) is one of the most important. It takes part in the metabolism, increases the body's resistance to infectious diseases. Found in vegetables, fruits, berries. Most of all in rosehips, black currants, citrus fruits, capsicum, potatoes, cabbage. Vitamin B-1 (thiamine) regulates carbohydrate and fat metabolism in the body. Rye bread, liver, kidneys, yeast, all kinds of vegetables, etc. are the richest in it. Vitamin B-2 (riboflavin) plays an important role in redox processes. Its deficiency leads to lethargy, fatigue, insomnia, impaired vision, neurasthenia, indigestion, growth retardation, hair loss. Milk, liver, eggs, grains, nuts, beets, apricots are rich in vitamin B-2. Water-soluble vitamins include B-3, B-6, B-12, P, PP, H, U.

Fat soluble vitamins: vitamin A necessary for normal vision, growth, increases the body's resistance to infectious diseases, favors the restoration of blood, protects the skin and mucous membranes from keratinization. A lot of vitamin A in milk, butter, egg yolk, cod liver. In plant foods, vitamin A is in the form of carotene. A lot of carotene in carrots, apricots, red peppers, pumpkins, peaches. Vitamin D(calciferol) regulates the absorption of calcium and phosphorus. With a lack of vitamin in children, rickets develops. It is found in fish oil, milk, cream, fish liver, brewer's yeast, mushrooms. Vitamin E(tocopherol) - protects vitamins from oxidation, participates in energy metabolism. It is necessary for dystrophy, neurasthenia, overwork, hypertension, dermatosis, psoriasis. This vitamin is called a reproductive factor (with its deficiency, infertility occurs). This vitamin is found in cereal germs, salads, vegetable oils (sea buckthorn, corn, soybean, etc.). Vitamin K(folloquinone) - is blood-clotting. It has a strong analgesic and antimicrobial effect, promotes healing of wounds, burns, frostbite. The source of vitamin K are: lettuce, green cabbage leaves, tomatoes, potatoes, cucumbers, beans, soybean oil.

Organic acids- give taste to products, contribute to the preservation of some of them. Organic acids are more commonly found in plant foods. These include: malic, citric, tartaric, oxalic acids; in products of animal origin - dairy.

Enzymes are protein substances that play a role in the metabolic process. Under their influence, all the life processes of the body occur. Enzymes are used in bakery, in cheese making, in obtaining fruit and berry juices, clarifying them.

Dyestuffs give color to food. Carotene causes orange color (carrots, apricots, etc.). Lycopene gives red color (tomatoes, apples), xanthophyll - yellow color (orange, egg yolk). Chlorophyll- green pigment, colors the leaves of plants, vegetables, fruits. Anthocyanins- pigments of various colors are found in the skin of plums, grapes, blueberries, lingonberries, beets.

pectin substances- pectin, protopectin, pectin acid - found in berries, fruits. In the presence of sugar and acid, pectin is able to form jelly,

used in the production of marmalade, marshmallow, confiture. Gelling ability is possessed by gooseberries, currants, cherry plums, etc.

Tannins- give products astringency, astringent taste. A lot of tannins in persimmon, quince, tea, coffee. Tannins are oxidized under the action of atmospheric oxygen and acquire dark brown color. Tannins have a bactericidal property, promote wound healing, strengthen the walls of blood vessels.

Food products also contain other substances: aromatic, extractive, phytoncides, etc.

Review questions:

1. List the organic and inorganic substances that make up food products.

2. Answer why the moisture content of some products is a mandatory indicator of quality.

3. Name the role of minerals in human nutrition.

4. Name the importance of vitamins in human nutrition.

5. List organic acids that have bactericidal properties.

6. Name the industry in which pectin substances are used.